Field of the Invention
The exemplary embodiments described herein are related to the field of low cost handheld and portable wireless short range communication systems that require higher frequency bands of operation to provide very high data throughput transmissions.
Background of the Invention
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Broadband wireless transmission is limited by the amount of power as well as the spectrum (bandwidth) allocated. In current wireless standards, both the power as well as the bandwidth is limited to avoid interference and to serve multiple wireless transmissions for civil and military use. Thus the achieved data rates have a limit. Although multiple-input-multiple-output (MIMO) technology has been used to enhance the data rates using multiple antennas at the receiver and transmitter sides, very high data rates that can ensure true digital video and multimedia transfer are still a major throughput bottleneck to higher transmission rates.
Wider bandwidth allocations can provide significant throughput improvements. Such wide spectrum is available at very high frequencies such as the 30-60 GHz and 70-90 GHz ranges. These bands cover millimeter waves (electromagnetic waves with wavelength of 10-1 mm). Millimeter waves suffer from very high attenuation when used in wireless links due to several channel conditions, and this restricted their use to point-to-point links and military use. Recently, these bands have been re-investigated for short range communications. Although the channel measurement curves show more than 15 dB/Km attenuation when operating at 60 GHz due to atmospheric absorption, the free space attenuation becomes much smaller when for indoor short range operation. This has triggered a totally new area of short range high data rate applications that can benefit from the extreme wideband at these very high frequencies.
For short range consumer electronics applications, the 28 GHz band of mm-wave spectrum has attracted several major wireless operators. This band that covers from 27-29.5 GHz is used for mobile, fixed satellite, fixed point-to-point and marine services across the world (USA, Europe, China and Korea). Path loss and atmospheric absorption are not as severe in this band as that of the 60 GHz band, in addition when used for short distance communications, it poses a potential candidate for multi-GHz bandwidth for very high throughput short range applications such as multimedia and video services. The high loss associated with the high frequency of operation can be compensated by the use of large aperture antennas or antenna arrays.
The design of antenna arrays at mm-wave frequencies is not a trivial task. Efficient as well as cost effective solutions are required for consumer electronic devices. The feeding structures of such arrays are also very challenging to design and optimize. Finally the integration between the antenna arrays and the feeding structures should be done with care.